1. NOTCH A person you have slept with and have no intentions of a relationship with, but you lie about loving them, wanting them, etc. just to keep sleeping with them.
2. A notch is a person who has slept with a lot of people and has nothing to show for it. They are not in a relationship and occasionally get the "notch" call to meet and have sex, but under the false pretense of romance and relationship.
I called up this girl I used to date and told her a bunch of mess about how I missed her and wanted to see her; just so I could hit. She's just a notch, nothing special.